Kaman Aerospace Corporation

Bobby L Ulich

R Norris Keeler

Albert J Lazzarini

Kent P Pflibsen

Gregory H Ames

Duane Smith

Charles H Kaman

John D Rather

Edward K Conklin

Kent Phlibsen

Robert J Mayerjak

Rudolph E Radau, Jr

Anthony D Gleckler

Silvio A Cardero

Lonnie K Calmes

Kirk J Daniels

Robert S Manthy

George Schafer

John McLean

Joseph Mangano

Edward K Conkun

John W Montgomery

William P Elkins

An imaging lidar system for underwater applications is presented which is well suited for imaging and detecting underwater targets suspended above and on the bottom in shallow and coastal water. The present invention provides the capability for rapid and reliable search, detection, classification and localization of objects in the surf zone which may present hazards to navigation and utilization of coastal areas as well as undesirable effluents and biological fouling of underwater objects. The present invention provides an improved bottom tracker, improved ability to deal with brightness variation and surface glint, and computerized real time detection algorithms.

Imaging lidar system for shallow and coastal water

An imaging UV/visible fluorosensing and Raman lidar system comprises an optical sensor for simultaneously measuring temporally, spatially and spectrally resolved laser backscatter from on the land, on or beneath the surface of bodies of water and in the atmosphere and utilizes 'active' interrogation or 'passive' interrogation for remotely and non-destructively probing the spectrally-dependent optical properties of a scene. In the 'active' mode, the optical sensor of this invention comprises a transmitter (preferably a tunable solid state laser) which emits pulses of coherent light through a variable or adjustable field-of-view telescope whereupon the light pulses are then propagated towards a scene (e.g., land, sea or atmosphere). Thereafter, laser backscatter is collected by a second variable field-of-view telescope and directed to an imaging system and spectrally dispersive optical subsystem.

Spectrally dispersive imaging lidar system

An imaging UV/visible fluorosensing and Raman lidar system comprises an optical sensor for simultaneously measuring temporally, spatially and spectrally resolved laser backscatter from on the land, on or beneath the surface of bodies of water and in the atmosphere that utilizes 'active' interrogation or 'passive' interrogation for remotely and non-destructively probing the spectrally-dependent optical properties of a scene. In the 'active' mode, the optical sensor comprises a transmitter (preferably a tunable solid state laser) which emits pulses of coherent light through a variable or adjustable field-of-view telescope whereupon the light pulses are then propagated towards a scene (e.g., land, sea or atmosphere). Thereafter, laser backscatter is collected by a second variable field-of-view telescope and directed to an imaging system and spectrally dispersive optical subsystem.

An imaging lidar system is presented which is adapted to decrease the backscattering at the receiver when a target is viewed in reflection and to increase the backscattered reflection when the target is viewed in obscuration by operating the airborne lidar imaging system bistatically in the former case, and monostatically in the latter case. In accordance with a first embodiment of the present invention, a retractible prism and remote reflecting mirror are used to direct the laser transmitter beam downward. The reflecting mirror is offset so that there is a finite angle between the transmitter optical path and the path of the light reflected back into the CCD framing camera. The angle can be varied by moving the reflecting mirror along a track or rail with the appropriate adjustment to the mirror so that the transmitter beam is completely captured and directed downward to illuminate the area viewed by the camera. In a second embodiment of the present invention, the camera is placed on runners and displaced from the transmitter beam. A control is inserted so that the transmitter optics are directed to the area imaged by the camera.

Imaging lidar system employing bistatic operation

A new and improved adaptive optics wavefront tilt sensor having both very high sensitivity and wide dynamic range is presented. In accordance with this invention, distortion is induced in each subaperture beam by passing a high f-number beam through a field lens having large amounts of spherical aberration. The distortion provides transition from a wide dynamic range, low sensitivity wavefront tilt measurement to a narrow dynamic range, high sensitivity wavefront tilt measurement. This beam is then impinged on a single photodector which provides at least one electrical signal indicative of centroid position.

High sensitivity-wide dynamic range optical tilt sensor

A novel data processing technique is provided for detecting and locating a target from a plurality of two-dimensional images generated by an imaging sensor such as an imaging lidar system. The present invention processes this series of two dimensional images (made with one or more imaging detectors) in an optimal statistical fashion to reliably detect and locate targets. This invention is a process by which the images are mathematically modified to reduce the deleterious effects of noise and thereby provide the highest possible probability of detection while simultaneously maintaining a very low probability of false alarm. The data processing technique described herein also provides an estimate of the reliability of the detection, the target location and an output image to be displayed for visual confirmation and perhaps classification by the operator. The method of the present invention includes some or all of the following steps: noise reduction, spatial filtering, noise parameter extraction, asymmetric threshold detection, contrast stretching, localization, recognition, range or depth determination and subimage mosaic generation. The present invention is particularly well suited for processing two dimensional images of underwater targets generated by an imaging sensor located on an airborne platform whereby the underwater target is precisely and accurately detected, located and identified.

Process for automatically detecting and locating a target from a

An imaging UV/visible fluorosensing and Raman lidar system comprises an optical sensor for simultaneously measuring temporally, spatially and spectrally resolved laser backscatter from on the land, on or beneath the surface of bodies of water and in the atmosphere. The present invention utilizes 'active' interrogation or 'passive' interrogation for remotely and non destructively probing the spectrally-dependent optical properties of a scene. In the 'active' mode, the optical sensor of this invention comprises a transmitter (preferably a tunable solid state laser) which emits pulses of coherent light through a variable or adjustable field-of-view telescope whereupon the light pulses are then propagated towards a scene (e.g., land, sea or atmosphere). Thereafter, laser backscatter is collected by a second variable field-of-view telescope and directed to an imaging system and spectrally dispersive optical subsystem.

A three dimensional range resolving imaging sensor is presented. The sensor comprises a transmitter for generating a light pulse which passes through beam homogenizer and a pair of Fresnel-Risley prisms. This pulse is then directed through an environmental window towards an object enveloped in a backscattering medium. A portion of the light pulse is reflected back towards the sensor. However, prior to detecting the return light pulse, a detector array is internally calibrated by exposure to a calibration pulse. This detector array preferably comprises a two-dimensional photo multiplier tube (PMT) array. A corresponding array of light tapers is disposed before the PMT array to increase the fill factor of the PMTs. Gain and offset corrections are made for each PMT from this exposure. The return pulse passes through the environmental window and impinges a pair of Fresnel-Risley scanner plates. These plates introduce a fixed angular deviation which is dependent on the orientation of the plates. This pulse then passes through a spectral bandpass filter and onto a collection mirror. The collected return pulse is then directed to the PMT array. The output of the PMT array comprises a plurality of electrical signals. These signals are conditioned and then processed by an image processor. The image processor provides a visual display which is available to an operator. Also, the image processor may perform automated target recognition and alert the operator when a target is detected.

Method and apparatus for three dimensional range resolving imaging

An imaging lidar system for underwater applications is Presented which is well suited for imaging and detecting underwater targets suspended above and on the bottom in shallow and coastal water. The present invention provides the capability for rapid and reliable search, detection, classification and localization of objects in the surf zone which may present hazards to navigation and utilization of coastal areas as well as undesirable effluents and biological fouling of underwater objects. The present invention employs an improved bottom tracker for accurately measuring the distance between the imaging lidar system and the bottom.

An underwater maneuverable vehicle is presented which carries an explosive charge and can be used for immediate removal or destruction of various menaces to navigation and other underwater hazards. The battery powered vehicle is air dropped from a platform which carries an imaging lidar system for detection and is operated and navigationally controlled in conjunction with an imaging lidar system. In accordance with an important feature of this invention, an optical lidar downlink is used to control the submerged underwater maneuverable vehicle from an airborne platform. The downlink is pulse spaced modulated. Command signals are secure, and are decoded aboard the vehicle. Control in speed, heading and depth, as well as command detonation are available using this technique.

Image lidar transmitter downlink for command guidance of underwater

An imaging lidar apparatus for detecting and imaging an object enveloped by a backscattering medium which is at least partially transmitting to light is presented. The imaging lidar apparatus is mounted on an airborne platform and including light pulse generating means, reflected light pulse detection means and computer control means. A discrete vehicle is towed by a cable connected to the airborne platform. The discrete vehicle houses optics for receiving or transmitting light pulses. Fiber optic communication may be used to transmit the light pulses along the cable between the airborne platform and the towed vehicle.

Airborne imaging lidar system employing towed receiver or transmitter

An airborne imaging lidar (light detection and ranging) sensor is provided which employs multiple pulsed laser transmitters, multiple gated and intensified array camera receivers, an optical scanner for increased field of regard, and a computer for system control, automatic target detection and display generation. The laser transmitters and multiple camera receivers are optically boresighted to the optical scanner (e.g., oscillating flat mirror) for an increased swath width perpendicular to the aircraft heading. The several laser transmitters are coupled for increased power and system sensitivity.

Imaging lidar system

An electro-optical camera system is presented. In accordance with the present invention, a light source (e.g. laser) is modulated by an electro-optic modulator (such as a Pockels cell) and transmitted out through an optical system toward a static target scene. The light backscattered from the target scene is then focused by the same optics back through the same Pockels cell onto a two-dimensional array camera such as a CCD or a CID (charge-couple device or charge injection device). A computer determines the frequency modulation period of each pixel in the array as the frequency of the electro-optic modulator is varied. This period is inversely proportional to the range of the target in the direction defined by the pixel location. Thus, all three spatial coordinates (two angles and a range) of each target area sensed by each pixel are determined. The computer will display the array of range data using a suitable output device such as a video display unit or a printer.

Range finding array camera

A wavefront aberration sensor includes a beam splitter, one or more aberration sensor modules and a photodetector for sensing total light power. The aberration sensor modules each provide two voltage outputs from a pair of photodetectors. Differences in the voltage pairs are normalized by the total light power to represent signed aberration amplitudes of phase aberrations present in an input optical beam. The aberration amplitudes may be combined in a digital computer to provide a reconstructed wavefront.

Apparatus for sensing wavefront aberration

A segmented mirror control system comprises an array of structural elements (e.g. mirrors) which can be actively positioned to maintain an accurate pre-determined overall shape. The present invention is 'active' and so may be characterized as an Active Segmented Mirror Control 'ASMC'. The segments of a mirror or the reflecting panels, in for example, a radiotelescope, may be continually adjusted with ASMC to provide an accurate reflecting mirror of very large diameter even when disturbed by external forces. ASMC is a closed loop control system. That is, an array of sensors is first used to measure differential position errors. This data is then processed to determine position actuator commands. Finally, these commands are used to move the segments until the sensors are nulled and the desired shape is obtained.

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Tucson, AZ, United States of America

Bobby L Ulich